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Lowstand Fans Formation and Their Hydrocarbon
Accumulation Since Middle Miocene, Yinggehai
and
Jiang, Tao, Xinong Xie,
This study
distinguishes fourth sequence from seismic data and reveals that the stratigraphical patterns of the Yinggehai
continental margin are mainly characterized by the progradational
slope prisms. In the Qiongdongnan area, however, the
slope margins show a stacking pattern in vertical or a little shift seaward, in
which a very wide shelf forms, a plentiful of gravitational slipping faults
and slump deposits develop. This kind of stratigraphical
architecture indicates that sediments at lower and base of slope position are
controlled by gravitational flow processes. The evolution of shelf-slope offers
the background of lowstand fans formation. The study
to stratigraphy and subsidence shows that the factors
impacting lowstand fans formation involve tectonic,
sea-level changes, sediment supply and climate. The dynamic modeling is
executed by Computer Fluid Dynamic software°ªFLUENT.
The simulation can distinctly display the forming process of lowstand fans including slope fan, basin floor fan and lowstand wedge and reveal the ingredients deciding the type
and scale of lowstand fans. Furthermore, because the
fluid velocity of deepwater turbidite has less change
scope and can be looked as a consant, on the
condition of given slope which is decided by local geology setting, grain size
controls the type and characteristics of lowstand
fans. The result may be used to estimate hydrocarbon reservoir based on the
characteristics of lowstand fans, which can be
gained by seismic data, and correlative wells. Finally, the models of
hydrocarbon accumulation in lowstand fans are
summarized since Middle Miocene in the Yinggehai and Qiongdongnan basins.